I'm sure that someone in their office read the books, but a lot of people don't pay much attention to the actual dates of the books, and only followed the dates when the books were actually published and released.

I guess I have a personal attachment to Harry's birthdate; we ALMOST shared the same birthdate (I was a bit late), and so I tend to think of it quickly. But either way, it's all OUR age group, and I think a lot of us get a kick out of that.